Prevention of frost formation on automatic controls



Jan. 22, 1935.. BJIG. ALDRIDGE ET AL 1,988,769

PREVENTION FROST FORMATION ON AUTOMATIC CONTROLS Filed Sept. 2, 1933 IN VEN TORS ATTORNEY Patented Jan. 22, 1935 PREVENTION OF FROST FORMATION ON AUTOMATIC @ONTBOLS Blair G. Aldridge and Edward G. Ragatz, Los .Angeles, Calif., assignors to Union Oil Company of California, Los Angelos, Calif a corporation of California Applieationseptember 2, 1933, Serial No. 687,95?

13 Claims.

The present invention relates to the art of re= frigeration, and more particularly it pertains to automatic control equipment adapted to handle both liquid substances maintained at extremely low temperatures and highly volatile materials :Tubjected to such low temperatures to liquefy In the art of refrigeration, and more particularly in the chilling of waxy oils to remove therefrom the wax constituents, it is frequently necessary to maintain the level of the refrigerant or of a mixture of the refrigerant and of the substance being chilled constant. Thus, the recently discovered method of dewaxing wax-containing oils consists, broadly stated, in-mixing this waxy oil with a liquefied but normally gaseous hydrocarbon such as liquid propane, butane, ether, etc. The mixture, maintained under a pressure sufficient to keep the diluent in a liquid state, is introduced into a chilling chamber. The pressure on the 'mixture is then lowered to evaporate-a portion of the diluent and thus chill the mixture to a temperature at which the wax precipitates. The wax is then withdrawn by any one of the well known methods, such as filtering, centrifuging or decanting. Although the proportion of liquefied but normally gaseous hydrocarbons and of the waxy oil being treated varies within comparatively large limits, depending upon the charactor of the oil being treated, etc., it has been found that the separation or, extraction of the wax from the thus chilled waxy oil is obtained most favorably when the ratio of the oil to the diluent-refrigerant is maintained constant for the specific oil. The above described evaporation of a portion of the diluent to chill the waxy oil naturally changes this ratio, thus necessitating the addition of new quantities of the diluent to maintain the ratio constant. This is usually made automatically by providing an automatic valve on the diluent-introducing line and by actuating this valve by means of a float within the chilling chamber, or within a special chamber communicating with this chilling chamber.

The above described equipment, however, is inefiicient and unreliable, and its functions are accompanied by many defects. Thus, the actuating means connecting the float with the automatic control valve are subject to'freezing either through the accumulation of frost on the equipment due to the lower temperatures used, or due to the refrigerating effect obtained by the leakage of small amounts of the highly volatile diluent through the packing glands used in conjunction with such float actuated equipment,

It is, therefore, an object of the presentinven= tion to obviate the above described defects, and to provide an automatic constant-level control ling means which are accurate and reliable. It is another object of the present invention to pro vide the above described type of refrigerating equipment with means which prevent the ireezing of such equipment and/or the accumulation of frost thereon.

It has now been found that the above and other objects may be obtained by enclosing the packing glands of the above described automatic controls, and by filling the thus enclosed space with some light gaseous, vaporous or liquid substance, such as light kerosene, liquefied 0r gaseous propane, dry air, etc., which will not freeze at the operating temperature. It has been further found that such enclosing of the vital operating parts 01 the equipment keeps the moisture-laden air away, thus preventing the accumulation of frost on the equipment, with the result that the equipment operates continuously.

Therefore, broadly stated, the invention resides in preventing frost formation upon the automatic controls of a refrigerating equipment by enclosing them in a bath of a gaseous, vaporous or liquid substance, such as propane, which does not congeal at the operating temperature.

The invention further resides in providing the liquid level controller with an insulated enclosure, thereby preventing the frost formation on the actuating parts of said controller, and the freezing thereof. The invention still further re sides in the filling of said enclosure with a substance, gaseous or liquid, which will not freeze or congeal at the low operating temperatures.

In its preferred form, the invention resides in a float controller communicating with a chamber the liquid level of which is to be regulated by a pilot valve. actuated by said liquid level controller, a line opening into the chamber and adapted to introduce thereinto the refrigerating substance, an automatic valve on said line and adapted to be actuated by the above pilot valve, and a casing enclosing a part of the liquid controller and the pilot valve and adapted to prevent both the frost formation thereon and the freezing thereof. The gaseous substance, such vas air, used to operate the automatic valve through the actuation of the pilot valve,- may be preferably treated to remove therefrom all of the moisture contained therein, thus further preventing freez ing of the equipment. The above described cas ing which encloses the pilot valve and the packing glands on the liquid level controller, may be ing into the casing obviously does not congeal or freeze at the operating temperatures, and at the same time prevents the freezing of the equipment by the contact thereof with moisture-laden air.

For a better understanding of the above described principles reference is now made to the accompanying drawing, the sole figure of which shows diagrammatically, and partly in section, a view of a preferred embodiment of the present invention. In this figure, the chilling or refrigerating chamber or tank 10 is provided with a refrigerant-introducing pipe 11 equipped with an automatic valve 12. As shown in the drawing, valve stem 13 of this valve passes through an enclosed chamber 14 which is provided with lines 15 and 16 for the introduction and discharge, respectively, of an anti-freeze liquid, such as light kerosene. The valve stem extends out of chamber 14 and is attached to a diaphragm ,17 which in turn is attached to a turtle-back shell 18 held stationary withrespect to the valve 12 by means of rods 19. A spring 20 is installed between diaphragm 1'7 and the upper end of chamber 14. If desired, chamber 14 may be provided with an insulation 21 to prevent heat radiation. The space 22 enclosed by the shell 18 and the diaphragm 17 communicates with a line 23, the other end of which opens into a pilot-valve 24 described further below.

The upper portionof the tank 10 is also provided with an ordinary remote control float valve. This consists of two lines 30 and 31 communicating the tank with the valves float chamber 32, I the lines leading into said chamber respectively from above and below the desired liquid level to be maintained in the tank. Float 33 in chamber 32 is attached to an arm 34, the other end of which is attached to a shaft 35 passing out of float chamber 32 through ordinary packing glands not shown in the drawing. Shaft 35, outside of said chamber 32, is equipped with a lever 36. One end of this lever carries a rod 37 having a weight 38 adapted to slide and be locked thereon, the purpose of the weighted rod being to counter-balance float 33 and arm 34. The other end of lever 36 is attached to valve stem 39 of the above described pilot valve 24.

A line 40 leads into this pilot valve and is adapted to introduce thereinto compressed air, or another gas, for the purpose of, actuating the automatic valve 12. A line 41 also leads from pilot valve 24 and is adapted to discharge air from line 23.

The operations of the above described structure are quite clear. Thus .it 'is obvious that a drop of the liquid level in tank 10 causes a similar and corresponding drop of float 33. This movement actuates arm 34 and shaft 35 and moves valve stem 39 to open pilot-"valve 24. This permits the passage of compressed air from line 40, through line 23 and into the space 22 of the automatic valve 12. The increased pressure thus exerted on diaphragm 17 moves valve stem 13 downwardly, against, the pressure of spring 20, and opens the valve in line 11 to introduce additional quantities of liquid into tank 10. When the atmosphere through line 41 and thus closes valve 12 in line 11. i

As stated above, the leakage of the highly volatile liquefied substance through the packing glands of the float controller causes the freezing of the actuating mechanism. Also, the contact of the chilled structure with the moist atmospheric air causes the formation of frost, which further hinders the proper functioning of the actuating mechanism. To prevent thesedisadvantages this actuating mechanism is enclosed. Thus as seen in the drawing, the float chamber 32 is provided witha casing 50 enclosing that portion of the chamber which carries the actuating mechanism. This casing also encloses the pilot valve 24, while the lines 23, 40 and 41 communicating with the pilot valve pass out of said casing through sealed joints. The casing is preferably provided with an insulation 51 and with an open-ended pipe 52 which acts either as a liquid seal oras an expansion and contraction chamber.

As stated above, casing 50 may be fllled with light kerosene, liquid propane, or any other liquid substance which does not congeal or freeze at the operating temperatures. In such a case, pipe 52 acts as an expansion and contraction chamber. However, it is also possible to fill casing 50 with a gaseous substance. Thus, the liquefied but normally gaseous hydrocarbon, which may be introduced and/or stored in tank 10, may be allowed to leak through the aforementioned packing glands in the float chamber 32 and fill casing 50 with a non-freezing substance not containing any moisture. In such a case, pipe 52 may be filled with a substance acting as a seal and at the same time permitting the discharge of any excess of such gas accumulating in casing 50. Any other gas, such as carbon dioxide, nitrogen, flue gas, dry air, etc., may also be used. Similarliquids or gases may also be introduced into the insulated space 14 of valve 12, these substances preventing the freezing of valve stem 13.

It is quite obvious that the compressed air, or any other gas, injected through line 40 to actuate diaphragm 17 of valve 12, may be treated first to remove therefrom any traces of moisture. Thus, this air may be passed through calcium chloride or an acid bath before it is injected through pilot valve 24 into the space 22. naturally prevents the freezing of the valves 12 and 24.

It is to be understood that the abovedisclosure is not to be construed as limiting but merely as descriptive of the generic invention, since many variations may be made by those skilled in the art within the scope of the following claims:

-We claim:

Such a treatment 1. In an apparatus for refrigerating liquids and V the like, an automatic control having actuable parts, a chamber enclosing said'actuable parts of said control and an anti-freezing moisture free substance within said chamber and surrounding the actuable parts of said control.

3. An apparatus as in claim l in which the non-congealing substance comprises a liquid.

4. An apparatus as in claim 1 in which the noncongealing substance comprises a hydrocarbon.

5. An apparatus as in claim 2 in which the substance is circulated through said chamber.

6. An apparatus for refrigerating liquids comprising automatic control means for admission of liquid, said control means including actuating parts, a chamber enclosing said actuating parts and an anti-freezing liquid within said chamber and surrounding said actuating parts of said control means to prevent frost from forming on said actuating parts.

7. An apparatus as in claim 6, in which the anti-freezing liquid is passed through the chamher.

8. In combination a container, a liquefied volatile material in said container under a pressure and temperature sumcient to maintain said substance in a liquid state, a conduit leading tosaid container, a control device having actuable portions and in communication with said conduit, a chamber enclosing said actuating portions of said control and in communication with said device, conduit and container, means for maintaining a substantially constant pressure in said chamber to permit leakage of liquid and vaporization of volatile material in said chamber, and means for removing said vaporized material from said chamber.

9. In combination with a container for a liquid maintained at a low temperature, an automatic control having actuable portions and being in communication with said container, a chamber enclosing said actuating portions of said control,

and means associated with said chamber and adapted to pass thereinto and therethrough a portion of the liquid from said first mentioned container.

10. A structure for automatically controlling the level of a liquid maintained at a low temperature, comprising a container for said liquid,

a float control communicating with said container and having operating parts, a chamber enclosing said operating parts of the float control, and a substance free from freezing constituents within said chamber.

11. A structure according to claim 10, wherein means are provided for passing a portion of the liquid from the container into and through the chamber enclosing the operating parts of the float control.

12. A structure for automatically controlling the level of a liquid maintained at a low temperature, comprising a container for said liquid, a float control communicating with said container and having operating parts, a line introducing the low temperature liquid into said container, a valve on said line, a pilot valve actuable by the control and adapted to actuate the valve in response to the movements of'said float control,

a-chamber enclosing the operating parts of the float control and of the pilot valve, and an antifreezing substance within said chamber.

13. In a structure according to claim 12, wherein the valve on the line introducing the low temperature liquid into the container is provided with means for preventing the freezing of said valve.

BLAIR G. ALDRIDGE. EDWARD G. RAGATZ. 

